Submitted by thatsjustfuntastic t3_11ef4oa in explainlikeimfive
PEVEI t1_jae70d8 wrote
Reply to comment by RhynoD in eli5 if light is a wave what medium does it travel through? by thatsjustfuntastic
"The map is not the territory."
"All models are wrong, some are useful."
RhynoD t1_jae7yth wrote
Fair. But on the other hand, if all we have is models, is it not fair to say that fields do kind of work that way?
PEVEI t1_jae8vjv wrote
No, because a tank of water isn't the same as a field, it's just a useful way to model some aspects of how fields behave within certain limits. Outside of the limits its designed to accurately model, allegories are more misleading than illuminating.
Take Newton's version of gravitation for example, it's a great model! For everything you're going to encounter on Earth and can measure with the instruments of the day, it was very accurate. The only way you could tell that there were holes in the model was through observation of things like the precession of Mercury's orbit. The reality however is that Newton's model is deeply wrong, gravity isn't a fundamental force which acts instantaneously across space.
That model was then replaced by Einstein's model of gravitation, in the form of his field equations, which describes gravity as an apparent force emerging from the curvature of spacetime. This apparent force no longer acts instantaneously, and these corrections explained Mercury's orbit and a lot more.
If you use Newton's model you can build rockets to visit planets in the Solar system. If you use Newton's model to build a GPS system though, it would be useless, without Relativistic corrections the system fails in days at the most. Einstein's model seems pretty much perfect, you need to go to some pretty exotic places to see where the model breaks down, such as the interior of a black hole.
But it's important to remember that models are what we use to illustrate reality, or make predictions about reality, but models are not reality.
The map is not the territory.
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